Systems and methods for measuring the purity of bales of recyclable materials

ABSTRACT

In one embodiment of the present invention, a system includes a radio frequency identification (RFID) reader that is configured to obtain identification information from a plurality of RFID tags respectively attached to the plurality of items. A computer is configured to receive the identification information, and use the identification information to identify the items having a RFID tag attached thereto, and determine a percentage of a desired type of item with respect to the plurality of items.

RELATED APPLICATION

This application is related to the following copending and commonlyassigned patent application, which is incorporated herein by referencein its entirety: “Systems and Methods for Indicating a Quality ofGrouped Items,” having application Ser. No. 11/515,789, and filed onSep. 6, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention relate to the field of collectingrecyclable materials and, more particularly, to systems and methods fordetermining the composition and purity of a quantity of recyclablematerials.

2. Background Description

To meet the growing problem of post-consumer goods disposal, manyrecyclable post-consumer goods are collected from the curbside and sentto a material recovery facility (MRF). MRFs are facilities where mixedrecyclable materials are sorted and baled for sale, and generally serveas drop-off and gross-sorting (and limited processing) points forrecyclable materials, so that sorted recyclable materials can betransported, for example, to a facility for subsequent processing.

Recyclable materials generally enter a MRF either in a single stream ordual stream. A single stream MRF may receive a mixture of commingledcontainers that may be made of glass, plastics, and/or metals, and fibermaterial that may include old news print (ONP) (e.g., newspaper andnewspaper inserts), old corrugated paper (OCC), old telephonedirectories (OTD), old magazines (OMG), junk mail and/or office paper. Adual stream MRF generally has separate commingled container and fibermaterial streams.

Generally, recyclable materials arriving at MRFs can be sorted intoindividual material categories, such as glass, plastic, steel, aluminum,paper, cardboard, and the like. In addition, clear glass can beseparated from colored glass, and plastics can be separated by type andcolor. Materials such as plastic, steel, aluminum, paper, and cardboard,can then be baled in a standard manner. Bales can be stored at an MRFuntil a buyer, such as a glass plant or paper recycling facility,purchases them.

While traditional MRFs typically utilize a dual stream configuration,the desire to reduce labor and other operational costs has been animpetus behind the trend toward single stream MRFs. However, sortedrecyclable materials produced by single stream MRFs can have a highercontamination level than sorted recyclable materials from dual streamMRFs. Thus, for example, bales of sorted plastic from a single streamMRF may have an average purity of 95% by weight, whereas bales of sortedplastic from a dual stream MRF may have an average purity of 97% byweight.

In known systems, bale-specific information regarding purity is notgenerally ascertainable until you break open the bale. Accordingly,bales are typically sold based on physical accessibility of the baleswithin a MRF at the time of shipment. Lack of information pertaining tothe purity of the bales can result in bales being rejected by thepurchaser and returned to a MRF, or downgraded by the purchaser. Thisforces MRFs to absorb the cost associated with the returned bale(s), orto refund a portion of the sales price, particularly for bales emanatingfrom single stream MRFs that generally have higher contamination ratesthan bales emanating from dual stream MRFs.

We have discovered that systems and methods for accurately andefficiently measuring the composition and purity of a bale and providingverifiable bale-specific information are needed. Such systems andmethods can be used to ensure the purity of bales, increase customersatisfaction, and generate price premiums for the bales that aredetermined to have, for example, a higher than average level of purity.

SUMMARY OF EMBODIMENTS OF THE INVENTION

Embodiments of the present invention relate to systems and methods formeasuring the purity of bales of recyclable material. Variousembodiments of the present invention use radio frequency identification(RFID) technology to determine the composition of a bale of waste itemsand to calculate the purity of a bale of recyclable material.

In one embodiment of the present invention, a system includes a radiofrequency identification (RFID) reader configured to obtainidentification information from a plurality of RFID tags respectivelyattached to at least a portion of a plurality of items. A computer isconfigured to receive the identification information, and use theidentification information to identify the items having a RFID tagattached thereto, and determine a percentage of a desired type of itemwith respect to the plurality of items. The system also include anoptical counter for counting a total number of the plurality of items.

The computer calculates a measurement of purity that includes a percentweight of items of the desired type among the plurality of items withrespect to a total weight of the plurality of items. The system alsoincludes or utilizes a scale for measuring the total weight of theplurality of items.

The computer is further configured to calculate a total weight of itemsof the desired type by identifying each of the items of the desired typeusing the identification information and determining a combined weightof each of the identified items. The computer is also configured tocalculate a total weight of items of the desired type by identifyingeach item other than the items of the desired type among the pluralityof items using the identification information, and subtracting a weightof each of the identified other items from the total weight of theplurality of items.

The system also includes or utilizes a baler that creates a balecomprising the plurality of items. The computer includes or utilizes arepository for storing identification information of a bale thatincludes the plurality of items, and, in connection with theidentification information of the bale, the percentage of the desiredtype of item with respect to the plurality of items.

The system also includes or utilizes a RFID tag programmer configured towrite the percentage onto a RFID tag associated with the bale. Thesystem also includes or utilizes a second RFID reader that reads theidentification information of the bale from the bale RFID tag, whereinthe computer receives the identification information and updates therepository indicating that the bale is no longer available.

In another embodiment of the present invention, a method includesreading identification information from a plurality of RFID tagsrespectively attached to at least a portion of a plurality of items, andreceiving the identification information at a computing device thatidentifies each of the items having a RFID tag attached thereto. Apercentage of a desired type of item is calculated with respect to theplurality of items. The method also includes baling the plurality ofitems to form a bale, and writing the calculated percentage onto a RFIDtag associated with the baled items. The percentage pertains to aquantity of items of the desired type among the plurality of items withrespect to a total quantity of the plurality of items.

The method also includes weighing the plurality of items. When weighingthe plurality of items, the calculated percentage pertains to a percentweight of items of the desired type among the plurality of items withrespect to a total weight of the plurality of items.

In addition, the method includes attaching to the bale a RFID tag havingthe calculated percentage written thereon, and storing in a datarepository the calculated percentage. The data repository can be updatedto reflect that a particular bale is no longer available.

BRIEF DESCRIPTION OF THE DRAWINGS

The Detailed Description of the Invention, including the description ofvarious embodiments of the invention, will be best understood when readin reference to the accompanying figures wherein:

FIG. 1 is an exemplary block diagram of an embodiment of a puritymeasurement system;

FIG. 2A is an exemplary data repository of a serial number contained ona radio frequency identification (RFID) tag;

FIG. 2B is an exemplary data repository providing product informationrespectively associated with the RFID tag serial numbers shown in FIG.2A;

FIG. 3A is a 96-bit EPC™ structure that can be used in conjunction withone or more embodiments of the present invention;

FIG. 3B is an exemplary repository that utilizes at least a portion ofthe data contained in FIG. 3A;

FIG. 4 is an exemplary arrangement of an optical reader that can be usedin conjunction with one or more embodiments of the present invention;

FIG. 5 is an exemplary data repository that contains bale specificinformation; and

FIG. 6 is an exemplary flow chart illustrating a method for measuringthe purity of bales of recyclable materials.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a block diagram depicting purity measurement system 100 thatcan be used in a material recovery facility (MRF). System 100 includesgeneral purpose computer 120, which in turn includes purity measurementsoftware 122 and application data repository 124. System 100 alsoincludes RFID reader-counter 128, and tag programmer 126.

Computer 120 can include industry standard components (not shown), suchas a user interface (e.g., a keyboard and a mouse) and display (e.g., amonitor), a processor, a storage device such as a standard hard disk, aCD-ROM and/or CD-RW drive(s), a clock device for providing timestampdata, and/or standard interfaces (e.g., USB ports).

FIG. 1 also includes final sort container 130, scale 136, and baler 138.Container 130 contains waste items 132, which can be glass containers,plastic containers, aluminum containers, ferrous items, fiber productssuch as paper and cardboard, and/or other types of waste items.Container 130 can be any type of container for collecting waste items132, 132 a, 132 b.

Waste items 132 can have item RFID tags 134 affixed. Each of RFID tags134 can contain identification information, such as a digital serialnumber identifying the corresponding recyclable item, and/or informationregarding the type of the item. RFID reader-counter 128 can be used tocount items 132 going into container 130, and, read tags 134 in order toextract the identification information contained therein. RFIDreader-counter 128 can send the extracted identification information tocomputer 120, which utilizes purity measurement software 122 andrepository 124 to obtain information regarding waste items 132, such asitem weight and type of material.

Reader-counter 128 can be a commercially available RFID tag readersystem, such as the TI RFID system, manufactured by Texas InstrumentsIncorporated (Dallas, Tex.). RFID reader-counter 128 is positioned sothat RFID tags 134 of waste items 132 are within its effective range.Waste items 132 are used to form or generate a bale 140. Multiple balesof waste items can be stored at a MRF as inventory before they are soldand removed from the MRF.

Purity measurement software 122 uses repository 124 to analyzeidentification information obtained from tags 134 using RFID reader 128.Repository 124 can include information regarding different types ofwaste items 134, such as item weight and type of material (e.g., glasscontainer, plastic container, aluminum container, or paper product). Inaddition, repository 124 can also include any other information, such asinformation regarding bales stored at the MRF.

FIGS. 2A and 2B, taken together, illustrate one example of repository124. FIG. 2A is a table indexed by serial numbers 202 and associatingserial numbers 202 with item type indexes 204. FIG. 2B is a tableindexed by item type indexes 204. The table in FIG. 2B containsinformation relating to weight 206, type of material 208, and item type210 for various types of items 132. Therefore, in this example, using aserial number 202 identifying a recyclable item, software 122 cancross-reference repository 124 to determine the weight 206 and type ofmaterial 208 of the recyclable item. If the serial number is 00004, asshown in FIG. 2A, software 122 can determine that the corresponding item204 is a 12 ounce aluminum can 210 weighing 5 grams 206.

Implementation of repository 124 is not limited to the exampleillustrated in FIGS. 2A and 2B; various implementations of repository124 can be used to achieve the same results. The implementation ofrepository 124 may also vary depending on the type of identificationinformation contained in RFID tags 134.

For example, FIG. 3A, generally at 300, illustrates the ElectronicProduct Code (EPC), which is a standard format for storingidentification information in RFID tags. The EPC is designed to replacethe Universal Product Code (UPC) currently utilized in conjunction withbarcodes. An EPC-96 code has four components:

(a) an 8-bit tag version number 302, indicating the tag type (e.g.,96-bit EPC Class 1);

(b) a 28-bit domain manager identifier 304, such as a number specifyingthe entity that administers the tag code (e.g., “ABC Co.”);

(c) a 24-bit object class identifier 306, such as a number specifyingthe type of product the RFID tag is attached to (e.g., “16 oz. Coca-Colabottle”); and

(d) a 36-bit unique identifier 308, which is a number that, incombination with the other EPC components, uniquely identifies the tag(and object).

If RFID tags 134 utilize, for example, the EPC as illustrated in FIG.3A, or a similar or related technique, repository 124 can be implementedaccordingly. For example, repository 124 can include a table asillustrated in FIG. 3B, containing entries indexed by the 28-bit domainmanager identifier 304 and the 24-bit object class identifier 306.Entries in the table can also include weight 206 and type of material208 associated with a certain type of recyclable item. Therefore, inthis example, after receiving an EPC-96 code containing domain manageridentifier 304 representing Company B and object class identifier (306)1, software 122 can cross reference the table in FIG. 3B and determinethat the corresponding item is a 12 ounce aluminum can weighing 5 grams.

Certain waste items, such as items 132 a, 132 b illustrated in FIG. 1,may not have RFID tags 134 respectively attached thereto. For example,paper products, such as newspaper and/or cardboard, may typically nothave RFID tags 134 attached thereto. For these items, as illustrated inFIG. 4, an optical counter 402 can be utilized to count the number ofwaste items 132 that will be included in any particular bale. An opticalcounter 402, such as the MSS Sapphire™ or MSS Aladdin™ optical sorters,manufactured by MSS, Inc., Nashville, Tenn., can be used. When a MSSSapphire™ or MSS Aladdin™ optical sorter is used, optical counter 402can be arranged to receive items from conveyor system 404. When items132, 132 a, 132 b move toward container 130 on a conveyer system 404 tobe collected and baled, optical counter 402 can be utilized to countitems 132 having RFID tags 134 affixed thereto, as well as items 132 a,132 b that do not have an RFID tag affixed thereto.

Scale 136 can be used to weight items 132, 132 a, 132 b. Scale 136 canbe a general industrial weighing scale, such as the Siltec WS2000L,distributed by Precision Weighing Balances (Bradford, Mass.).

Returning now to FIG. 1, baler 138 can be used to transform loose items132 to a baled commodity, as represented by bale 140, upon which a baleRFID tag 142 can be affixed. Baler 138 can be any standard equipmentthat is used to compress and bind a recyclable material, such asaluminum, plastic or paper items 132, 132 a, 132 b. Baler 138 can be,for example, a 1060XDVB Baler by Wastecare Corporation (Atlanta, Ga.),which is an industrial, high-capacity, high-volume baler. Bale 140includes items 132, 132 a, 132 b that are bound tightly or wrapped, asis the industry standard for recyclable materials. Bale RFID tag 142 isan RFID tag device that can be written by tag programmer 126. Tagprogrammer 126 can be a reader/writer device, such as the SkyeModule™ M1device supplied by SkyeTek, Inc. (Boulder, Colo.), that can writeinformation to RFID tag 134.

Additionally, FIG. 1 depicts transport vehicle 110, which in turnincludes computer 112, RFID reader 114, communications link 116, andonboard scale 118. Vehicle 110 is, for example, a conventional haulingtruck that is used to carry and deliver recyclable material bales.Typically, vehicle 110 picks up recyclable material from an originatorpoint such as a MRF and delivers the recyclable material to an awaitingcustomer, such as a glass or paper recycling facility.

Onboard computer 112 can be a general-purpose computer. In someembodiments, computer 112 is a mobile computing device, such as onesupplied by Glacier Computing (New Milford, Conn.) or by MobileComputing Corp. Inc. (Mississauga, Ontario), that is physically integralto vehicle 110. Computer 112 can include industry standard components(not shown), such as a user interface and display, a processor, astorage device such as a standard hard disk, a CD-ROM and/or CD-RWdrives, a clock device for providing timestamp data, and/or standardinterfaces (e.g., USB ports) for connecting to reader 114, scale 118,and/or communications link 116.

RFID reader 114 can be a commercially available RFID tag reader system,such as the TI RFID system, manufactured by Texas Instruments (Dallas,Tex.). In one or more embodiments, RFID reader 114 is a wired orwireless handheld reader that can be easily moved by an operator ofvehicle 110. In one or more embodiments, RFID reader may be separatefrom (e.g., removable from) transport vehicle 110.

Communications link 116 can be any standard wired or wirelesscommunications device and/or network that allow data to be exchangedbetween computer 112 and computer 120. Onboard scale 118 can be anycommercially available scale mechanism, such as the weigh-in motionweighing system, supplied by Mobile Computing Corp. Inc. (Mississauga,Ontario).

In operation, RFID reader-counter 128 reads items RFID tags 134 affixedto items 132 before or after they are deposited into final sortcontainer 130. Software 122 utilizes repository 124 (e.g., asillustrated in FIGS. 2A, 2B, and 3B) to identify items 132. Furthermore,software 122 determines a measurement of purity of items 132, as will bedescribed in connection with FIG. 5. In addition, scale 136 can obtainand transmit the combined weight of items 132, 132 a, 132 b to computer120, which can store the combined weight in repository 124.

Baler 138 receives items 132, 132 a, 132 b within container 130, andtransforms items 132, 132 a, 132 b into bale 140 in a standard manner.Tag programmer 126 can write bale specific information (e.g., puritymeasurement determined by software 122) onto bale RFID tag 142.

As bale 140 is loaded onto vehicle 110, bale RFID tag 142 can be read byRFID reader 114. Onboard scale 118 can also be used to weigh bale 140.Onboard computer 112 can store the bale specific information andtransmit the information to computer 120 via communications link 116, sothat computer 120 can keep track of which bales have been loaded ontovehicle 110 and which bales remain at the MRF.

For example, FIG. 5 is a table 500 containing bale specific informationthat can be stored in repository 124. The table includes entriesrepresenting bales created in the MRF. An entry in the table can includea bale ID 502, the type of items 210 in the corresponding bale, the typeof material 208 in the bale, the weight of the bale 504, and a puritymeasurement 506 (e.g., a weigh percent) for the bale. An entry in table500 can also include a status field 508 indicating whether thecorresponding bale is still in the MRF, or whether it has been shippedout to a buyer.

FIG. 6 is a flow chart illustrating a method 600 for measuring thepurity of bales and of recyclable materials. The following describesmethod 600 as being performed using system 100, generally with referenceto FIG. 1.

At step 610, a number of waste items 132, 132 a, 132 b are received.Items 132, 132 a, 132 b can be the output of a sort process, andtherefore can include a high percentage of objects of the same type. Forexample, items 132, 132 a, 132 b can include a high percentage ofaluminum containers. However, the sort process can be imperfect, so thata relatively small percentage of contaminants or other material types(e.g., glass containers, paper products), with or without RFID tags 134affixed thereon, can be present.

At step 612, a sort criterion can be established using puritymeasurement software 122. A sort criterion can specify one or multipletypes of material that is intended to be included in bale 140 thatincludes items 132, 132 a, 132 b. Measurement of the purity of bale 140can be based on the percentage of items 132 that satisfy the sortcriterion, or the percentage weight of items 132 that satisfy the sortcriterion. Waste material or items 132 a, 132 b not satisfying the sortcriterion may be viewed as contamination. Different purchasers of balesmay require different purity levels. For example, one purchaser ofaluminum bales may require a maximum of 2% contamination (by weight oritem count), while another may be willing to accept up to 5%contamination.

At step 614, items 132, 132 a, 132 b are identified and counted. RFIDreader-counter 128 counts the number of items 132 that have RFID tags134 affixed thereon, and reads identification information, such asweight 206, from tags 134. If desirable, optical counter 402 can beutilized to count the total number of items 132, 132 a, 132 b, asdiscussed in connection with FIG. 4. If optical counter 402 and RFIDreader-counter 128 are used in combination, the number of items 132 thathave RFID tags 134 attached thereon and the number of untagged items 132a, 132 b can both be ascertained. Identification information obtained byreader-counter 128 can be stored in repository 124.

If it is determined at decision step 618 that the number of untaggeditems 132 a, 132 b is not negligible, then, at step 616, the totalweight of items 132, 132 a, 132 b can be measured by scale 136 andstored in repository 124. At step 622, the weight percent is calculatedbased on the weight 206 information obtained in step 614 and the totalweight obtained in step 616.

For example, if the sort criterion of step 612 is set as plasticcontainers, software 122 can query repository 124 using theidentification information from each RFID tag 134, to determine the type210 and weight 206 of each corresponding item. Software 122 can then sumthe weight of each of items 132 that is determined to be a plasticcontainer to obtain the total weight of plastic containers. Thepercentage weight of items that satisfies the sort criterion can then becalculated as:X=(ΣW _(i))/T _(WEIGHT)

where X is the percentage weight of the items that meet the sortcriterion;

W_(i) represents the individual weight of each item that meets the sortcriterion; and

T_(WEIGHT) is the total weight of all items 132, 132 a, 132 b, ascaptured by scale 136.

If RFID reader-counter 128 reads and accounts for 10,000 plasticcontainers, and repository 124 indicates that each container weighs 0.05pounds, then the total weight of plastic containers is 500 pounds. Ifscale 136 records the weight in container 130 as being approximately 560pounds, the purity measurement can then be calculated, according to theabove formula, as X=(500 pounds)/(560 pounds)=0.89 (and 11%contaminants).

Unlike plastic containers, glass bottles often break during a sortprocess, resulting in untagged broken glass pieces being received atstep 610, as well as tagged pieces that have less weight than what thetags indicate. However, by statistical approximation, the total weightof the glass pieces can be calculated by summing the weight of theoriginal unbroken bottles. Therefore, the weight percent may becalculated as described above.

The sort criterion of step 612 may also be set to a type of items 132 a,132 b that do not have RFID tags affixed thereon. For example, wasteitems received in step 610 may include mostly of paper products that areuntagged. If the number of untagged items 132 a, 132 b excluding thepaper products is negligible, the total weight of the paper products canbe calculated by subtracting the weight of items 132 from the totalweight of items 132, 132 a, 132 b obtained in step 616. The weightpercent can then be calculated by dividing the total weight of the paperproducts by the total weight of items 132, 132 a, 132 b.

If at decision step 618 it is determined that the number of untaggeditems is negligible (e.g., if optical counter 402 in FIG. 4 countedsubstantially the same number of items as counted by reader-counter 128in FIG. 1), then, at step 620, software 122 can determine or approximatethe purity of bale 140 in terms of the weight percentage of certaintypes of recyclable items without measuring the total weight of items132, 132 a, 132 b as in step 616. This is a consequence of the totalweight of items 132, 132 a, 132 b being approximated by summing thecalculated weight of each of items 132. For example, software 122 mayquery repository 124 using identification information 202 obtained fromeach of RFID tags 134 to determine the weight of each of items 132. Thepercentage weight can then be approximated by calculation by dividingthe total weight of items 132 that meet the sort criterion by the totalweight of all items 132.

Other measurements of purity, such as the percentage of items 132 thatmeet the sort criterion of step 612, may also be calculated. Forexample, after step 614, software 122 can query repository 124 usingidentification information 202 obtained from each of RFID tags 134 todetermine a material type for each of items 132 that has an RFID tagaffixed thereon, and count the number of items 132 for a particularmaterial type specified in the sort criterion. The percentage of items132 that meet the sort criterion of step 612 can be calculated asfollows:X=RFID _(C1)/(RFID _(C1) +RFID _(C2))

-   -   where X is the percentage of items that meet the sort criterion;    -   RFID_(C1) is the number of items that meet the sort criterion;        and    -   RFID_(C2) is the number of items that do not meet the sort        criterion.

As an example, the sort criterion may be set as aluminum containers.Assuming that all (or substantially all) aluminum containers have tags134 attached thereto, software 122 determines that 10,000 items meet thesort criterion. In step 614, the total number of items 132, 132 a, 132 bis determined to be 10500 (i.e., there are 500 other items, tagged oruntagged). At step 620, the percentage of items 132 that meet the sortcriterion is therefore,X=RFID _(C1)/(RFID _(C1) +RFID _(C2))X=10,000/(10,000+500)X=0.95 or 95% aluminum containers (and 5% other)

At step 624, the purity measurement can be stored in repository 124. Atstep 626, items 132, 132 a, 132 b in container 130 can be loaded intobaler 138 and compressed into bale 140.

At step 628, computer 120 can retrieve data that represents the contentsof bale 140 from repository 124 (e.g., the sort criterion, total weight,and/or the purity measurement calculated) and use tag programmer 126 towrite this data to bale RFID tag 142, which can be affixed to bale 140.Computer 120 may further update MRF bale inventory information, so MRFpersonnel are informed or can access repository 124 to determine, forexample, that a bale with certain purity has been added to the MRF baleinventory.

At step 630, bale 140 with tag 142 affixed thereon can be loaded ontovehicle 110. At step 632, vehicle RFID reader 114 can read tag 142, andonboard computer 112 can store the data obtained from tag 142.

At step 634, data read from RFID tags (e.g., tag 142) associated withbales (e.g., bale 140) that are loaded on vehicle 110 can be transferredfrom onboard computer 112 to computer 120 via communications link 116.This data represents all bales loaded on vehicle 110. Computer 120 mayfurther update MRF inventory information (e.g., as illustrated in FIG.5), so MRF personnel can know exactly which bales remain in the MRFinventory.

Other embodiments, extensions, and modifications of the ideas presentedabove are comprehended and within the reach of one skilled in the artupon reviewing the present disclosure. Accordingly, the scope of thepresent invention in its various aspects should not be limited by theexamples and embodiments presented above. The individual aspects of thepresent invention, and the entirety of the invention should be regardedso as to allow for modifications and future developments within thescope of the present disclosure. The present invention is limited onlyby the claims that follow.

1. A system for determining a purity of a bale comprising a plurality ofrecyclable waste items, comprising: a radio frequency identification(RFID) reader configured to obtain identification information from aplurality of RFID tags respectively attached to at least a portion ofthe plurality of recyclable waste items; and a computer configured toreceive the identification information, and query a repository using theidentification information to determine type and weight of each of therecyclable waste items having the RFID tag attached thereto, anddetermine a percentage of a desired type of item with respect to theplurality of recyclable waste items.
 2. The system of claim 1, furthercomprising an optical counter for counting a total number of theplurality of items.
 3. The system of claim 1, wherein the computercalculates a measurement of purity comprising a percent weight of itemsof the desired type among the plurality of items with respect to a totalweight of the plurality of items.
 4. The system of claim 3, furthercomprising a scale for measuring the total weight of the plurality ofitems.
 5. The system of claim 3, wherein the computer is furtherconfigured to calculate a total weight of items of the desired type byidentifying each of the items of the desired type using theidentification information and determining a combined weight of each ofthe identified items.
 6. The system of claim 3, wherein the computer isfurther configured to calculate a total weight of items of the desiredtype by identifying each item other than the items of the desired typeamong the plurality of items using the identification information, andsubtracting a weight of each of the identified other items from thetotal weight of the plurality of items.
 7. The system according to claim1, further comprising a baler that creates the bale comprising theplurality of items.
 8. The system of claim 1, wherein the computerstores in the repository identification information of a bale comprisingthe plurality of items, and, in connection with the identificationinformation of the bale, the percentage of the desired type of item withrespect to the plurality of items.
 9. The system of claim 8, furthercomprising a RFID tag programmer configured to write the percentage ontoa RFID tag associated with the bale.
 10. The system of claim 9, furthercomprising a second RFID reader that reads the identificationinformation of the bale from the bale RFID tag, wherein the computerreceives the identification information and updates the repositoryindicating that the bale is no longer available.
 11. A method fordetermining a purity of a bale comprising a plurality of recyclablewaste items, the method comprising: reading identification informationfrom a plurality of radio frequency identification (RFID) tagsrespectively attached to at least a portion of the plurality ofrecyclable waste items; querying a repository using the identificationinformation from the plurality of RFID tags to determine type and weightof each of the recyclable waste items having the RFID tag attachedthereto; calculating a percentage of the desired type of recyclablewaste item with respect to the plurality of recyclable waste items;baling the plurality of recyclable waste items to form the bale; andwriting the calculated percentage onto a RFID tag associated with thebaled recyclable waste items.
 12. The method of claim 11, wherein thepercentage pertains to a quantity of items of the desired type among theplurality of items with respect to a total quantity of the plurality ofitems.
 13. The method of claim 11, further comprising weighing theplurality of items.
 14. The method of claim 13, wherein the calculatedpercentage pertains to a percent weight of items of the desired typeamong the plurality of items with respect to a total weight of theplurality of items.
 15. The method of claim 11, further comprisingattaching to the bale a RFID tag having the calculated percentagewritten thereon.
 16. The method of claim 15, further comprising storingin the data repository the calculated percentage.
 17. The method ofclaim 16, further comprising updating the data repository to reflectthat a particular bale is no longer available.